It is well known to transmit, as communications signals, digital data within a modulated carrier waveform. Timing information is included within the communication signals to provide sampling points for an analog to digital converter (ADC) to recover the digital data. While being transmitted, the modulated carrier waveform suffers from distortion. Thus, when received, the signal should be filtered to improve the signal-to-noise ratio.
In a conventional modem, for example, the signal filtering and timing recovery tasks are performed by separate functional units. Analog-to-digital conversion circuitry ("analog front end") samples the received modulated carrier waveform responsive to a sampling clock to convert the carrier waveform to a digitized replica. A processor executes a program to recover the digital data from the digitized replica using a timing signal recovered from the modulated carrier waveform. In addition, a control function (usually executed within a processor) analyzes the recovered timing signal, and in response thereto, adjusts the phase of the sampling by the analog front end.